Terho Heikkinen,1 Emilia Ojala,1 and Matti Waris21Department of Pediatrics, University of Turku and Turku University Hospital, and 2Department of Virology, University of Turku, Finland

We analyzed the burden of RSV in a prospective cohort study of children aged ≤13 years during two consecutive respiratory seasons in Turku, Finland (2231 child-seasons of follow-up). Of 6001 medically attended respiratory infections, 302 (5%) were caused by RSV. Per 1000 children, the average annual RSV incidence rates among children aged <3, 3-6, and 7-13 years were 275, 117, and 46, respectively. In children aged <3 years, acute otitis media developed in 58%, and 66% of children in this age group received antibiotics. The mean duration of RSV illness was longest (13.0 days) and the rate of parental work absenteeism highest (136 days per 100 children with RSV) in children aged <3 years. The burden of RSV is particularly great among outpatient children aged <3 years, and young children are an important target group for the development of RSV vaccines and antivirals.